What makes these endurance athletes different from others who pursue similar challenges as part of a team, or while competing against fellow athletes?
Carlson set off solo from Newfoundland in a custom-made boat and landed at the Isles of Scilly a little more than 38 days later.
On that run, Carlson always had other runners and support staff around.
Photograph: Jessica GoldmanBefore her 91-day run, Goldman had completed two long, solo bike rides, as well as ultra races.
With food, everything is ready for you at the store.”While some ultra runners find comfort in the proximity of their fellow athletes, Goldman said it adds a layer of pressure.